Forskolin is a labdane diterpene that is produced by the Indian Coleus plant (Coleus forskohlii). Forskolin is commonly used to raise levels of cyclic AMP (cAMP) in the study and research of cell physiology. Forskolin resensitizes cell receptors[dubious – discuss] by activating the enzyme adenylyl cyclase and increasing the intracellular levels of cAMP. cAMP is an important signal carrier necessary for the proper biological response of cells to hormones and other extracellular signals. It is required for cell communication in the hypothalamus/pituitary gland axis and for the feedback control of hormones. Cyclic AMP acts by activating cAMP-sensitive pathways such as protein kinase A and Epac. Forskolin can also be used to promote nerve repair by increasing cAMP concentrations. Forskolin can activate or upregulate the proliferation of Schwann cells in culture, together with Fibroblast growth factor or Transforming Growth Factor-Beta.